This invention relates to atmospheric gas burners.
In conventional atmospheric gas burners, such as are used as surface units in ranges and cooktops, the main burner ports are generally of uniform size and shape and equally spaced around the periphery of the burner head. Examples of such burners are shown in U.S. Pat. Nos. 4,810,188, 3,301,311, and 3,817,689.
A problem which an occur with such burners, particularly when employed in so-called spill-proof or sealed gas burner arrangements (referring to the lack of an opening in the cooktop surface around the base of the burner to prevent spillage of food soils into the area beneath the cooktop) is that delayed ignition with a utensil in position over the burner can result in an uncontrolled combustion phenomenon characterized by a large flame envelope and shock waves accompanied with an objectionably high level of noise. Additionally, under normal operating conditions when the burner is adjusted to certain heat settings, typically a relatively low setting, the flame stands close to the burner resulting in potentially excessive burner head temperatures which in extreme instances could melt the burner.
A burner having a portion arrangement which varies from the conventional uniform port size arrangement of the aforementioned patents, is disclosed in British Patent Specification 796,167 published Jun. 4, 1958. In this burner the ports are equally spaced but different port sizes are employed to control the physical size of the flame. In particular, smaller ports are employed to provide starter flames in the areas proximate the pan support grid to avoid or limit impingement of the flame on the grid, to avoid quenching of the flame and the higher CO emissions associated with such quenching. However, such an arrangement does not address either the aforementioned uncontrolled combustion problem or the high temperature problem.
It is therefore a primary object of the present invention to provide an improved gas burner for surface cooking appliances, which alters the combustion process so as to yield slower and more controlled combustion under delayed ignition conditions without compromising stable combustion and satisfactory emission performance under normal operating conditions.
It is a further object of the invention to provide an improved burner of the aforementioned type which contributes to lower burner operating temperatures at the lower heat settings.
It is a further object of the invention to provide an improved gas burner of the aforementioned type which does not add substantially to the cost or structural complexity of conventional burners.